Effect of Elevated Temperature and Low Radiation on Growth and Yield of Basmati Rice (Oryza Sativa L.)

Five basmati rice varieties were subjected to high thermal and low light stress (3 ⁰C higher than ambient temperature and 20% reduction in light intensity) during various growth phases to assess the effect of high temperature and low radiation on growth, yield and yield attributes of these varieties. High thermal and low light stress throughout the entire growth period (tillering to maturity) caused highest reduction in grain yield followed by plant exposure to such stress from tillering to anthesis, while heat and low light stress from anthesis to maturity did not show any detrimental effect on grain yield. Among varieties, Taraori Basmati and Pusa Basmati 1 showed greater tolerance to high thermal and low radiation stress and thereby manifested higher grain yield under such stress. The reduction in grain yield was mainly due to significant reduction in grains/panicle owing to marked increase in spikelet sterility under high temperature and low light stress as the number of panicles/pot and 1000 grain weight were least affected by such stress.